Dear Sir/Madam…

I am tried to calculate the Thermal Conductivity of Diamond at 300 K.

But in journals, it saying that Diamond having very high values of Thermal conductivity and at 300K its about 2000W/(mK).

But in my calculation, i m getting the value of Thermal Conductivity less than 100 W/(mK)…

I am giving the detailed input script of my Calculation.

Can U give me any suggestion of this mismatching between Theory, Experiment & Simulation.

# Sample LAMMPS input script for thermal conductivity of Diamond

units metal

variable T equal 300

variable V equal vol

variable dt equal 0.001

variable p equal 100 # correlation length

variable s equal 10 # sample interval

variable d equal $p*$s # dump interval

# convert from LAMMPS metal units to SI

variable kB equal 1.3806504e-23

variable eV2J equal 1.602177e-19

variable A2m equal 1.0e-10

variable ps2s equal 1.0e-12

variable convert equal {eV2J}*{eV2J}/{ps2s}/{A2m}

# setup problem

dimension 3

boundary p p p

lattice diamond 3.5626 orient x 1 0 0 orient y 0 1 0 orient z 0 0 1

region box block 0 5 0 5 0 5

create_box 1 box

create_atoms 1 box

mass 1 12.0107

pair_style tersoff

pair_coeff * * SiC.tersoff C

timestep ${dt}

thermo $d

# equilibration and thermalization

velocity all create $T 102486 mom yes rot yes dist gaussian

fix NVT all nvt temp $T $T 10 drag 0.2

run 8000

# thermal conductivity calculation, switch to NVE if desired

#unfix NVT

#fix NVE all nve

reset_timestep 0

compute myKE all ke/atom

compute myPE all pe/atom

compute myStress all stress/atom virial

compute flux all heat/flux myKE myPE myStress

variable Jx equal c_flux[1]/vol

variable Jy equal c_flux[2]/vol

variable Jz equal c_flux[3]/vol

fix JJ all ave/correlate $s $p d &
c_flux[1] c_flux[2] c_flux[3] type auto file J0Jt.dat ave running
variable scale equal {convert}/${kB}/$T/$T/$V*s*

{dt}

variable k11 equal trap(f_JJ[3])*{scale}
variable k22 equal trap(f_JJ[4])*{scale}
variable k33 equal trap(f_JJ[5])*${scale}

thermo_style custom step temp v_Jx v_Jy v_Jz v_k11 v_k22 v_k33

run 100000

variable k equal (v_k11+v_k22+v_k33)/3.0

variable ndens equal count(all)/vol

print “average conductivity: $k[W/mK] @ T K, {ndens} /A^3”

Hoping forward for your reply

Many Thanks & Kind Regards

Siby